This invention relates to radio frequency (RF) power modules and, in particular, to integrated circuit preamplifiers. Preamplifiers are a class of amplifiers commonly used in radio communication.
Portable, cellular radios have obtained wide spread use in modern society Unfortunately, these radios are often too large and too heavy for a user to carry around comfortably. A smaller radio would be highly advantageous.
Much of the bulkiness of present cellular radios is dedicated to power modules which amplify or receive signals or to the size of the battery required for those power modules Designers have been unable to this point to design a monolithic microwave integrated circuit (MMIC) amplifier for radio frequencies between 100 MHz and 1.5 GHz. Instead, hybrid circuits requiring transmission lines and sometimes large bipolar junction transistors have been utilized. The aforementioned transmission lines take up a lot of space. These prior art hybrid circuits are also very expensive to manufacture.
A MMIC preamplifier should be comprised of gallium arsenide (GaAs), since GaAS devices, unlike silicon (Si) devices, have a natural insulating property which prevents loss of some of the RF signal. A Si MMIC would suffer some loss of the RF signal which would severely decrease operational efficiency of the radio. However, while GaAS MMIC preamplifiers are preferable, designers have been unable to achieve required amplification in them for RF applications. Only 8-12 GHz amplifiers are presently available. Devices which work in the 300 MHz-1.5 GHz range are required to be useful for many applications since currently 450 MHz and 900 MHz frequencies are the most commonly used frequencies in cellular radio communications